使用 Lodash 将 JavaScript 数组拆分为块

我需要将一个 JavaScript 数组分割成 n大小的块。

例如: 给定这个数组

["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"]

n等于4，输出应该是:

[ ["a1", "a2", "a3", "a4"],
["a5", "a6", "a7", "a8"],
["a9", "a10", "a11", "a12"],
["a13"]
]

我知道纯 JavaScript解决方案可以解决这个问题，但是因为我已经在使用 Lodash了，所以我想知道 Lodash 是否为这个问题提供了更好的解决方案。

编辑:

我创建了一个 JsPerf 测试来检查下划线解决方案有多慢。

83541 次浏览
小开

For Underscore based solution try this:

var data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
var n = 3;
var lists = _.groupBy(data, function(element, index){
return Math.floor(index/n);
});
lists = _.toArray(lists); //Added this to convert the returned object to an array.
console.log(lists);

Using the chain wrapper method you can combine the two statements as below:

var data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
var n = 3;
var lists = _.chain(data).groupBy(function(element, index){
return Math.floor(index/n);
}).toArray()
.value();
小开

try this one it is much more practical (for example, if you would want to split the array based on amount of items to be container in each sub array):

function chunk(arr, start, amount){
var result = [],
i,
start = start || 0,
amount = amount || 500,
len = arr.length;


do {
//console.log('appending ', start, '-', start + amount, 'of ', len, '.');
result.push(arr.slice(start, start+amount));
start += amount;


} while (start< len);


return result;
};

and the use in your case:

var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17],
chunked = chunk(arr, 0, Math.floor(arr.length/3)); //to get 4 nested arrays


console.log(chunked);

and another case:

var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17],
chunked = chunk(arr, 0, 3); // to get 6 nested arrays each containing maximum of 3 items


console.log(chunked);
小开
最佳答案

Take a look at lodash' chunk: https://lodash.com/docs#chunk

const data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
const chunks = _.chunk(data, 3);
console.log(chunks);
// [
//  ["a1", "a2", "a3"],
//  ["a4", "a5", "a6"],
//  ["a7", "a8", "a9"],
//  ["a10", "a11", "a12"],
//  ["a13"]
// ]
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

小开

A possibly simpler expression:

const coll = [ "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9" ];
const n = 2;
const chunks = _.range(coll.length / n).map(i => coll.slice(i * n, (i + 1) * n));
console.log(chunks);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

小开

Underscore supports _.chunk() natively as of version 1.9.0.

const data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
const chunks = _.chunk(data, 4);
console.log(chunks);
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore.js"></script>


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